yii ztree 报错 [ 新手入门 ]

Undefined index: class

D:\www\ems\protected\extensions\ztree\zTree.php(184)

172     /**
173      * 初始化
174      * @see CJuiWidget::init()
175      */
176     public function init()
177     {
178         $path=dirname(__FILE__).DIRECTORY_SEPARATOR.'assets';
179         $this->baseUrl=Yii::app()->getAssetManager()->publish($path);
180         $this->themeUrl    = $this->scriptUrl    = $this->baseUrl;
181         parent::init();
182         
183         $this->htmlOptions['id']=$this->id;
184         $this->htmlOptions['class']    .= ' tree';
185     
186         if ($this->iconsCss)
187         {
188             $this->cssFile[]    = 'zTreeIcons.css';
189         }
190         
191         if ($this->treeNodeKey !== null)
192         {
193             $this->options['treeNodeKey']        = $this->treeNodeKey;
194         }
195         if ($this->treeNodeParentKey !== null)
196         {

有人知道是什么情况吗？